Magic Mishap Dilemmas

Here’s a mechanic: when a player casts a spell, the GM can give them a choice between the usual cost of spell casting (losing an inventory slot to a "fatigue" condition in Adventure Hour!/Cairn; burning a spell slot, etc.) OR taking on some creative and situationally appropriate spell mishap effect. 

Using an ice cream wand to turn the goblin into a giant popsicle? It worked, but you rolled a mishap; do you want to take on a fatigue or suffer from a brain freeze for 2d6 X 10 minutes?